Melanoma is one of the most malignant skin cancers. It begins in the skin's pigmentproducing cells called melanocytes which undergo a malignant alteration and have tendency to metastasize both lymphatic and hematogenous. Melanoma accounts for 5% of primary skin cancers but is responsible for 80% of deaths from skin cancer. There are 580 new cases of melanoma diagnosed in Croatia each year. Melanoma can arise from normal appearing skin or in precursor lesions. It typically affects the skin but can also occur in mucous membranes, eyes and the nervous system. Giant dysplastic nevi present at birth have a very high potential to become malignant. The majority of melanomas are black or brown but can also be non pigmented. There are three stages of melanoma: melanoma in situ (in this phase melanocytes become malignant within the basal layer of the epidermis), the radial phase (considers the lateral expansion) and the vertical growth phase (with invasion into dermis). According to the clinical characteristics and histological picture there are 4 basic types of melanomas: superficial spreading melanoma – SSM, nodular melanoma – NM, lentigo maligna melanoma – LMM, and acral lentiginous melanoma – ALM. The most common is superficial spreading melanoma which is most likely to occur on the back in men and the legs in women. Clinical signs that may indicate melanoma are asymmetrical form, irregular, jagged or notched edges, colour that can vary from light to dark brown and a size usually larger than 6 mm in diameter. The prognosis for melanoma is closely related to tumor thickness, the presence of ulceration and the increase in mitotic rate. The 5-year relative survival rate is as follows: stage 0 - 97%, stage I – 90-95% / 75%, stage IIA – 80% / 65%, stage IIB – 72-75% / 50 – 60%, stage IIC – 53% / 44%, stage III – 45%, and stage IV – 10%. Depending on one or more distant metastases in stage IV, the survival rate after one year declines. Other unfavourable prognostic factors are the presence of regression, microsatellites, older age and male gender. Therapy is always radical surgery that cuts 1 to 3 cm in healthy tissue. If regional lymph node metastases are detected, lymph node dissection can be performed. Early detection of melanoma and education are keys to successful treatment. Individuals who are diagnosed with melanoma or have a family history of melanoma or dysplastic nevus syndrome (a large number of dysplastic nevi) should be dermatologically checked at least once a year.